Hybrid parallel/serial bus interface

ABSTRACT

A hybrid serial/parallel bus interface has a data block demultiplexing device. The data block demultiplexing device has an input configured to receive a data block and demultiplexes the data block into a plurality of nibbles. For each nibble, a parallel to serial converter converts the nibble into serial data. A line transfers each nibble&#39;s serial data. A serial to parallel converter converts each nibble&#39;s serial data to recover that nibble. A data block reconstruction device combines the recovered nibbles into the data block. The data block is employed by a gain controller.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No. 09/990,060, filed Nov. 21, 2001, now U.S. Pat. No. 7,069,464 which is incorporated by reference as if fully set forth.

FIELD OF INVENTION

The present invention relates to data bus transfers. In particular, the invention relates to reducing the number of lines to transfer bus data for gain control.

BACKGROUND

The invention relates to bus data transfers. In particular, the invention relates to transfer of bus data for operating a gain controller (GC).

One example of a bus used to transfer data is shown in FIG. 1. FIG. 1 is an illustration of a receive and transmit gain controllers (GCs) 30, 32 and a GC controller 38 for use in a wireless communication system. A communication station, such as a base station or user equipment, transmits (TX) and receives (RX) signals. To control the gain of these signals, to be within the operating ranges of other reception/transmission components, the GCs 30, 32 adjust the gain on the RX and TX signals.

To control the gain parameters for the GCs 30, 32, a GC controller 38 is used. As shown in FIG. 1, the GC controller 38 uses a power control bus, such as a sixteen line bus 34, 36, to send a gain value for the TX 36 and RX 34 signals, such as eight lines for each. Although the power control bus lines 34, 36 allow for a fast data transfer, it requires either many pins on the GCs 30, 32 and the GC controller 38 or many connections between the GCs 30, 32 and GC controller 38 on an integrated circuit (IC), such as an application specific IC (ASIC). Increasing the number of pins requires additional circuit board space and connections. Increasing IC connections uses valuable IC space. The large number of pins or connections may increase the cost of a bus depending on the implementation.

Accordingly, it is desirable to have other data transfer approaches.

SUMMARY

A hybrid serial/parallel bus interface has a data block demultiplexing device. The data block demultiplexing device has an input configured to receive a data block and demultiplexes the data block into a plurality of nibbles. For each nibble, a parallel to serial converter converts the nibble into serial data. A line transfers each nibble's serial data. A serial to parallel converter converts each nibble's serial data to recover that nibble. A data block reconstruction device combines the recovered nibbles into the data block.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is an illustration of a RX and TX GC and a GC controller.

FIG. 2 is a block diagram of a hybrid parallel/serial bus interface.

FIG. 3 is a flow chart for transferring data blocks using a hybrid parallel/serial bus interface.

FIG. 4 illustrates demultiplexing a block into a most significant and least significant nibble.

FIG. 5 illustrates demultiplexing a block using interleaving.

FIG. 6 is a block diagram of a bi-directional hybrid parallel/serial bus interface.

FIG. 7 is a diagram of an implementation of one bi-directional line.

FIG. 8 is a timing diagram illustrating start bits.

FIG. 9 is a block diagram of a function controllable hybrid parallel/serial bus interface.

FIG. 10 is a timing diagram of start bits for a function controllable hybrid parallel/serial bus interface.

FIG. 11 is a table of an implementation of start bits indicating functions.

FIG. 12 is a block diagram of a destination controlling hybrid parallel/serial bus interface.

FIG. 13 is a table of an implementation of start bits indicating destinations.

FIG. 14 is a table of an implementation of start bits indicating destinations/functions.

FIG. 15 is a block diagram of a destinations/functions controlling hybrid parallel/serial bus interface.

FIG. 16 is a flow chart for start bits indicating destinations/functions.

FIG. 17 is a block diagram for a positive and negative clock edge hybrid parallel/serial bus interface.

FIG. 18 is a timing diagram for a positive and negative clock edge hybrid parallel/serial bus interface.

FIG. 19 is a block diagram of a 2-line GC/GC controller bus.

FIG. 20 is a block diagram of a 3-line GC/GC controller bus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a block diagram of a hybrid parallel/serial bus interface and

FIG. 3 is a flow chart of hybrid parallel/serial bus interface data transfer. A data block is to be transferred across the interface from node 1 50 to node 2 52, (54). A data block demultiplexing device 40 receives the block and demultiplexes it into i nibbles for transfer over i data transfer lines 44, (56). The value for i is based on a tradeoff between number of connections and transfer speed. One approach to determine i is to first determine a maximum latency permitted to transfer the data block. Based on the allowed maximum latency, a minimum number of lines required to transfer the block is determined. Using the minimum number of lines, the lines used to transfer the data is selected to be at least the minimum. The lines 44 may be the pins and their associated connections on a circuit board or connections on an IC. One approach to demultiplex into nibbles divides the block into a most significant to a least significant nibble. To illustrate for an eight bit block transfer over two lines as shown in FIG. 4, the block is demultiplexed into a four bit most significant nibble and a four bit least significant nibble.

Another approach interleaves the block across the i nibbles. The first i bits of the block become the first bit in each nibble. The second i bits become the second bit in each nibble and so on until the last i bits. To illustrate for an eight bit block over two connections as shown in FIG. 5, the first bit is mapped to the first bit of nibble one. The second bit is mapped to the first bit of nibble two. The third bit is mapped to the second bit of nibble one and so on until the last bit is mapped to the last bit of nibble two.

Each nibble is sent to a corresponding one of i parallel to serial (P/S) converters 42, (58), converted from parallel bits to serial bits, and transferred serially across its line, (60). On the opposing end of each line is a serial to parallel (S/P) converter 46. Each S/P converter 46 converts the transmitted serial data into its original nibble, (62). The i recovered nibbles are processed by a data block reconstruction device 48 to reconstruct the original data block, (64).

In another, bidirectional, approach, the i connections are used to transfer data in both directions as shown in FIG. 6. Information data may be transferred in both directions or information may be sent in one direction and an acknowledgment sent back in the other direction. A data block for transfer from node 1 50 to node 2 52 is received by the data block demultiplexing and reconstruction device 66. The demultiplexing and reconstruction device 66 demultiplexes the block into i nibbles. i P/S converters 68 convert each nibble into serial data. A set of multiplexers (MUXs)/DEMUXs 71 couples each P/S converter 68 to a corresponding one of the i lines 44. At node 2 52, another set of MUXs/DEMUXs 75 connects the lines 44 to a set of S/P converters 72. The S/P converters 72 convert the received serial data of each nibble into the originally transmitted nibbles. The received nibbles are reconstructed by a data block demultiplexing and reconstruction device 76 into the original data block and output as the received data block.

For blocks transferred from Node 2 52 to Node 1 50, a data block is received by the data block demultiplexing and reconstruction device 76. That block is demultiplexed into nibbles and the nibbles are sent to a set of P/S converters 74. The P/S converters 74 convert each nibble into serial format for transfer across the i lines 44. A Node 2 set of MUXs/DEMUXs 75 couples the P/S converters 74 to the i lines 44 and a Node 1 set of MUXs/DEMUXs 71 couples the lines 44 to i S/P converters 70. The S/P converters 70 convert the transmitted data into its original nibbles. The data block demultiplexing and reconstruction device 66 reconstructs the data block from the received nibbles to output the received data block. Since data is only sent in one direction at a time, this implementation operates in a half duplex mode.

FIG. 7 is a simplified diagram of one implementation of bidirectional switching circuits. The serial output from the node 1 P/S converter 68 is input into a tri-statable buffer 78. The buffer 78 has another input coupled to a voltage representing a high state. The output of the buffer 78 is the serial data which is sent via the line 85 to a Node 2 tri-statable buffer 84. A resistor 86 is coupled between the line 85 and ground. The Node 2 buffer 84 passes the serial data to a Node 2 S/P converter 72. Similarly, the serial output from the Node 2 P/S converter 74 is input into a tri-statable buffer 72. That buffer 72 also having another input coupled to a high voltage. The serial output of that buffer 82 is sent via the line 85 to a Node 1 tri-statable buffer 80. The Node 1 buffer 80 passes the serial data to a Node 1 S/P converter 70.

In another implementation, some of the i lines 44 may transfer data in one direction and the other i lines 44 transfer data in another direction. At Node 1 50, a data block is received for transmission to Node 2 52. Based on the data throughput rate required for the block and the traffic demand in the opposite direction, j, being a value from 1 to i, of the connections are used to transfer the block. The block is broken into j nibbles and converted to j sets of serial data using j of the i P/S converters 68. A corresponding j Node 2 S/P converters 72 and the Node 2 data block separation and reconstruction device 76 recovers the data block. In the opposite direction, up to i-j or k lines are used to transfer block data.

In a preferred implementation of the bidirectional bus for use in a gain control bus, a gain control value is sent in one direction and an acknowledgment signal is sent back. Alternately, a gain control value is sent in one direction and a status of the gain control device in the other direction.

One implementation of the hybrid parallel/serial interface is in a synchronous system and is described in conjunction with FIG. 8. A synchronous clock is used to synchronize the timing of the various components. To indicate the start of the data block transfer, a start bit is sent. As shown in FIG. 8, each line is at its normal zero level. A start bit is sent indicating the beginning of the block transfer. In this example, all the lines send a start bit, although it is only necessary to send a start bit over one line. If a start bit, such as a one value, is sent over any line, the receiving node realizes that the block data transfer has begun. Each serial nibble is sent through its corresponding line. After transfer of the nibbles, the lines return to their normal state, such as all low.

In another implementation, the start bits are also used as an indicator of functions to be performed. An illustration of such an implementation is shown in FIG. 9. As shown in FIG. 10, if any of the connections's first bits are a one, the receiving node realizes block data is to be transferred. As shown in the table of FIG. 11 for a GC controller implementation, three combinations of start bits are used, “01,” “10” and “11.” “00” indicates a start bit was not sent. Each combination represents a function. In this illustration, “01” indicates that a relative decrease function should be performed, such as decreasing the data block value by 1. A “10” indicates that a relative increase function should be performed, such as increasing the data block value by 1. A “11” indicates an absolute value function, where the block maintains the same value. To increase the number of available functions, additional bits are used. For example, 2 starting bits per line are mapped to up to seven (7) functions or n starting bits for i lines are mapped up to i.sup.n+1−1 functions. The processing device 86 performs the function on the received data block as indicated by the starting bits.

In another implementation as shown in FIG. 12, the start bits indicate a destination device. As illustrated in FIG. 13 for a two destination device/two line implementation, the combination of start bits relates to a destination device 88–92 for the transferred data block. A “01” represents device 1; a “10” represents device 2; and a “11” represents device 3. After receipt of the start bits of the data block reconstruction device 48, the reconstructed block is sent to the corresponding device 88–92. To increase the number of potential destination devices, additional start bits may be used. For n starting bits over each of i lines, up to i.sup.n+1−1 devices are selected.

As illustrated in the table of FIG. 14, the start bits may be used to represent both function and destination device. FIG. 14 shows a three connection system having two devices, such as a RX and TX GC. Using the start bit for each line, three functions for two devices is shown. In this example, the start bit for line 1 represents the target device, a “0” for device 1 and a “1” for device 2. The bits for connections 2 and 3 represent the performed function. A “11” represents an absolute value function; a “10” represents a relative increase function; and a “01” represents a relative decrease. All three start bits as a zero, “000,” is the normal non-data transfer state and “001” is not used. Additional bits may be used to add more functions or devices. For n starting bits over each of i lines, up to i.sup.n+1−1 function/device combinations are possible.

FIG. 15 is a block diagram for a system implementing the start bits indicating both function and destination device. The recovered nibbles are received by the data block reconstruction device 48. Based on the received start bits, the processing device 86 performs the indicated function and the processed block is sent to the indicated destination device 88–92.

As shown in the flow chart of FIG. 16, the start bits indicating the function/destination are added to each nibble, (94). The nibbles are sent via the i lines, (96). Using the start bits, the proper function is performed on the data block, the data block is sent to the appropriate destination or both, (98).

To increase the throughput in a synchronous system, both the positive (even) and negative (odd) edge of the clock are used to transfer block data. One implementation is shown in FIG. 17. The data block is received by a data block demultiplexing device 100 and demultiplexed into two (even and odd) sets of i nibbles. Each set of the i nibbles is sent to a respective set of i P/S devices 102, 104. As shown in FIG. 17, an odd P/S device set 102, having i P/S devices, has its clock signal inverted by an invertor 118. As a result, the inverted clock signal is half a clock cycle delayed with respect to the system clock. A set of i MUXs 106 select at twice the clock rate between the even P/S device set 104 and the odd P/S device set 102. The resulting data transferred over each connection is at twice the clock rate. At the other end of each connection is a corresponding DEMUX 108. The DEMUXs 108 sequentially couple each line 44 to an even 112 and odd 110 buffer, at twice the clock rate. Each buffer 112, 110 receives a corresponding even and odd bit and holds that value for a full clock cycle. An even 116 and odd 114 set of S/P devices recover the even and odd nibbles. A data block reconstruction device 122 reconstructs the data block from the transferred nibbles.

FIG. 18 illustrates the data transfer over a line of a system using the positive and negative clock edge. Even data and odd data to be transferred over line 1 is shown. The hatching indicates the negative clock edge data in the combined signal and no hatching the even. As shown, the data transfer rate is increased by two.

FIG. 19 is a preferred implementation of the hybrid parallel/serial interface used between a GC controller 38 and a GC 124. A data block, such as having 16 bits of GC control data (8 bits RX and 8 bits TX), is sent from the GC controller 38 to a data block demultiplexing device 40. The data block is demultiplexed into two nibbles, such as two eight bit nibbles. A start bit is added to each nibble, such as making 9 bits per nibble. The two nibbles are transferred over two lines using two P/S converters 42. The S/P converters 46 upon detecting the start bits convert the received nibbles to parallel format. The data block reconstruction device reconstructs the original 16 bits to control the gain of the GC 124. If a function is indicated by the start bits, such as in FIG. 11, the AGC 124 performs that function on the received block prior to adjusting the gain.

FIG. 20 is another preferred implementation for a hybrid parallel/serial converter, using three (3) lines, between a GC controller 38 and a RX GC 30 and TX GC 32. The GC controller 38 sends a data block to the GC 30, 32 with proper RX and TX gain values and start bits, such as per FIG. 14. If the start bits per FIG. 14 are used, Device 1 is the RX GC 30 and Device 2 is the TX GC 32. The data block demultiplexing device 40 demultiplexes the data block into three nibbles for transfer over the three lines. Using the three P/S converters 42 and three S/P converters 46, the nibbles are transferred serially over the lines and converted into the original nibbles. The data block reconstruction device 48 reconstructs the original data block and performs the function as indicated by the start bits, such as relative increase, relative decrease and absolute value. The resulting data is sent to either the RX or TX GC 30, 32 as indicated by the start bits. 

1. A gain control (GC) system comprising: a GC controller for producing a data block having n bits representing a gain value; i lines for transferring the data block from the GC controller to a GC, where 1<i<n; a data block demultiplexing device for demultiplexing the data block into a plurality of nibbles, each nibble being transferred over a different line of the i lines, wherein appended to each nibble is a start bit, wherein the start bits of said nibbles collectively indicate a mathematical function; and the GC having means for receiving the data block, a data block reconstruction device for combining the nibbles into the data block and means for adjusting a gain of the GC using the gain value of the data block based on the mathematical function.
 2. The GC system of claim 1, wherein the GC controller includes a converter for converting the n bits into a plurality of groups of bits, each group being serially transmitted over one of said i lines.
 3. A gain control (GC) system comprising: a GC controller for producing a data block having n bits representing a gain value; i lines for transferring the data block from the GC controller to a GC, where 1<i<n; and the GC having means for receiving the data block and adjusting a gain of the GC using the gain value of the data block; wherein a mathematical function indicated by the start bits collectively includes one of a relative increase, a relative decrease and an absolute value function.
 4. A gain control (GC) system comprising: a GC controller for producing a data block having n bits representing a gain value; i lines for transferring the data block from the GC controller to a GC, where 1<i<n; a data block demultiplexing device for demultiplexing the data block into a plurality of nibbles, each nibble being transferred over a different line of the i lines, wherein appended to each nibble is a start bit; and the GC having means for receiving the data block, a data block reconstruction device for combining the nibbles into the data block; wherein: the GC includes a receiver (RX) GC and a transmitter (TX) GC; and the start bits collectively indicate whether the data block is sent to the RX GC or TX GC.
 5. A method comprising: producing a data block by a gain control (GC) controller, the data block having n bits representing a gain value; demultiplexing the data block into a plurality of nibbles, each nibble for transfer over a different line of the lines, appending to each nibble a start bit wherein the start bits of said nibbles collectively indicate a mathematical function; transferring the data block from the GC controller to a GC over i lines where 1<i<n; receiving the data block at the GC; and adjusting a gain of the GC using the gain value of the data block.
 6. The method of claim 5, further comprising: converting the n bits into a plurality of groups of bits; and serially transmitting each group over one of said i lines.
 7. A method comprising: producing a data block by a gain control (GC) controller, the data block having n bits representing a gain value; demultiplexing the data block into a plurality of nibbles, each nibble for transfer over a different line of the lines, appending to each nibble a start bit wherein the start bits of said nibbles collectively indicate a mathematical function; transferring the data block from the GC controller to a GC over i lines where 1<i<n; receiving the data block at the GC; and adjusting a gain of the GC using the gain value of the data block, wherein a mathematical function indicated by the start bits includes one of a relative increase, a relative decrease and an absolute value function.
 8. A method comprising: producing a data block by a gain control (GC) controller, the data block having n bits representing a gain value; demultiplexing the data block into a plurality of nibbles, each nibble for transfer over a different line of the lines, appending to each nibble a start bit; transferring the data block from the GC controller to a GC over i lines where 1<i<n; receiving the data block at the GC; and adjusting a gain of the GC using the gain value of the data block, wherein the GC comprises: a receive GC and a transmit GC and the start bits collectively indicate whether the data block is sent to the receive GC or transmit GC. 